1. Field of the Invention
The present invention relates to a storage control device, storage device and storage device system and, more particularly, to a storage control device, storage device and storage device system that control refresh according to the temperature conditions of dynamic memories.
2. Description of the Related Art
A dynamic memory stores information by the presence or absence of an electric charge held by capacitors. This type of memory requires a refresh that is composed of reading out the data stored in the memory and rewriting the data before the charge is lost due to a leak current. On the other hand, a leak current in a dynamic memory is known to have a temperature dependence which causes the leak current to diminish at low temperatures and increase at high temperatures.
Therefore, when the refresh frequency is set according to the leak current flow at high temperatures, this frequency is excessively high if left unchanged, thus resulting in wasted power consumption. For this reason, a technique has been proposed that is designed to change the refresh frequency based on temperature information obtained by detecting the memory temperature (refer, for example, to Japanese Patent Laid-Open No. 2005-158222 (FIG. 1) and Japanese Patent Laid-Open No. 2005-235362 (FIG. 2)).